Move parts of lib/entity/ to wikidata-sdk

[nichtich]

validate_and_format_data.js and included parts should be moved to wikidata-sdk and made public to expand the flexible format of edit-entity to the more strict, consistent and verbose entity format. This is the opposite of simplify with additional reduction (see maxlath/wikibase-sdk#40). Maybe name it expand?

[maxlath]

Sorry for the late answer.

The problem with transferring this feature is that the format expansion done in wikibase-edit depends on fetching properties datatypes, while wikibase-sdk is purposefully not doing http requests internally, keeping it a dependency-free nodejs/browser agnostic lib. That said, wikibase-edit already has those capacities, and could maybe expose a function to do this expansion, independently from actually doing the edit. I would be curious to know your use-case: is that still a need you have?